Effect of statins on lipoprotein receptor expression in cell lines from human mast cells and basophils

Statins are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase and widely used to treat hyperlipidaemia. Apart from their direct lipid-lowering effects, statins may also influence lipid metabolism through modulation of low-density lipoprotein (LDL) receptors. Basophils and mast cells have been reported to express LDL receptors and have been implicated in atherogenesis. The aim of this study was to investigate the effects of statins on the interactions of 125I-LDL with purified primary human blood basophils, a human basophil cell line, KU812, and a human mast cell line, HMC-1.

Direct binding experiments were carried out with the primary basophils and KU812 as well as HMC-1 cells before and after pretreatment of the cells with atorvastatin, simvastatin, or cerivastatin. The effects of these three statins on the LDL-uptake and degradation as well as on thymidine incorporation in the cells were also studied.

Primary basophils, HMC-1 and KU812 cells expressed two classes of LDL binding sites. Exposure to atorvastatin, simvastatin or cerivastatin increased significantly ( P<0.05) the number of 125I-LDL binding sites on primary basophils and HMC-1 as well as KU812 cells. The effects of the statins were dose dependent. The statins also enhanced the uptake and degradation of LDL in primary basophils, HMC-1 and KU812 cells. The increase in the number of LDL binding sites induced by statins was abolished by mevalonic acid (200 micromol/l). Statins had no effect on the thymidine incorporation into the cells in an unstimulated condition.

Our results provide evidence for the upregulation of LDL binding sites on human basophils and mast cells by statins. We hypothesise that effects of statins on the lipid metabolism might also involve basophils and mast cells.